Adding a new empty column to a table

Node Development
1

Hi,

I'm beginning to use Knime and I have finished to read me all available information about it, but I have a basic problem. I'm trying to add a empty column to a table unsuccessfully.

The task I want to do it is to introduce new columns in a table with the information collected by another program, which is executed through the node. But, as first step, I need to be able to add a new empty column. And for that, I had modified the following funtions of NodeModel.

 

@Override
    protected BufferedDataTable[] execute(final BufferedDataTable[] inData,
            final ExecutionContext exec) throws Exception {
        ColumnRearranger rearranger = new ColumnRearranger(inData[0].getDataTableSpec());
        BufferedDataTable result = exec.createColumnRearrangeTable(inData[0], rearranger, exec);
        return new BufferedDataTable[]{result};
    }
    
    private ColumnRearranger createColumnRearranger(final DataTableSpec spec)
    throws InvalidSettingsException {
        ColumnRearranger result = new ColumnRearranger(spec);
        DataColumnSpecCreator appendSpecCreator = new DataColumnSpecCreator("NewColumn", StringCell.TYPE);
        DataColumnSpec appendSpec = appendSpecCreator.createSpec();      
        result.append(new SingleCellFactory(appendSpec){
            public DataCell getCell (final DataRow row){
                DataCell resultCell = row.getCell(0);
                if (resultCell.isMissing()) {
                    return DataType.getMissingCell();
                }
                return resultCell;
            }
        });
        return result;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected DataTableSpec[] configure(final DataTableSpec[] inSpecs)
            throws InvalidSettingsException {
        ColumnRearranger rearranger = createColumnRearranger(inSpecs[0]);
        return new DataTableSpec[]{rearranger.createSpec()};
    }

 

If anyone has had problems to receive information collected by other program executed through the node, I would like to know it since it's my next step.

Thank you so much

2

Use the transpose node, add an empty node and transpose back.

3

Sometimes, the setting for adding particular values in the add empty rows do not work. In that case add them with missing values and use the missing value node later.